1. Field of the Invention
The present invention relates to a medical knife which prevents a doctor from feeling the glare of illumination light used in an operation by reducing the reflection of the light as well as prevents deterioration of the cutting quality of the knife in the operation.
2. Description of the Related Art
Microscopic operations represented by an ophthalmic operation are basically executed by observing an affected area while enlarging it under a microscope. In this case, a problem arises in that it is difficult for a doctor to execute the operation because the light, which illuminates the affected area, is reflected on the surface of a medical knife and makes it difficult for the doctor to observe the affected area. To solve the above problem, there has been provided a medical knife which permits a doctor to easily observe an affected area by composing the entire surface of the knife of a non-reflecting surface. The non-reflecting surface is composed of a surface on which fine concavities and convexities are formed so that the light, which is directly reflected to the eyes of the doctor, can be suppressed by diffusely reflecting the light. In the medical knife arranged as described above, however, when the knife pierces living body tissue, friction is increased between the concavities and the convexities and the living body tissue, and further a problem also arises in that the sharpness of the knife for dissecting the living body tissue is lost because concavities and convexities are also formed on a cutting edge, and thus the cutting quality of the knife is deteriorated. When the cutting quality is deteriorated, it is difficult for an operator to form an incision wound which in agreement with his or her image, that is, it is difficult for the operator to form an incision wound having a self-closing property for permitting the incision wound to close by itself. This may adversely affect the curing of the incision wound after the operation.
Under the above circumstances, generally doctors select a medical knife depending on whether they put high priority on the cutting quality of the knife by enduring reflection of light or put high priority on reduction of reflected light by enduring deterioration of the cutting quality of the knife.
To solve the above problem, there has been proposed surgical knives whose surface, which is caught in a field of view when they are used in an operation under a microscope, is composed of a portion subjected to a reflection preventing treatment and a portion not subjected to the treatment (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-57980). In the above surgical knives, the lower surface of a cutting edge formed around the periphery of the knife is entirely subjected to the reflection preventing treatment except a slanting surface constituting the cutting edge, and the upper surface of the cutting edge is composed of a slanting surface constituting the cutting edge and a roughly ground surface formed along the slanting surface constituting the cutting edge inwardly of it, and a central flat surface, which continues to the inside and the back side of the roughly ground surface and is composed of a surface subjected to the reflection preventing treatment.
In the knives according to the art disclosed in JP-A No. 2001-57980, since only the slanting surface constituting the cutting edge is composed of the reflecting surface, no light is reflected from the surfaces other than the slanting surface constituting the cutting edge. Accordingly, a workload on a doctor can be reduced because the amount of light, which is reflected when an affected area is dissected, is reduced. However, even the knives arranged as described above are not yet perfect, and it has been required to develop a medical knife which reduces an amount of reflected light and has excellent cutting quality.